The present invention relates to a subassembly mounting device for oscillatingly mounting a range extender on a body and/or a chassis of a motor vehicle.
Additional assemblies in an electric vehicle, which increase the range of the vehicle, are known as so-called range extenders. The most frequently used range extenders are internal combustion engines, which drive a generator. The generator, in turn, supplies current to the battery and the electric motor. Because of the limited battery capacity and the limited charging rate, today electric vehicles normally have shorter ranges than vehicles with an internal combustion engine. An additional aggravating factor with an electric vehicle is that the vehicle is ready for use again only after an ex ended charging time of approximately 1-2 hours, contrary to the very fast refueling process with conventional vehicles. The range extenders are therefore used to extend the time during which the vehicle can be used continuously, that is the time between charging cycles, and therefore the operating range. The electric vehicle can be operated without range extenders during daily commuter traffic.
Highly varied mounting embodiments for the engine and/or the transmission of motor vehicles are known. These mounts can permit vibrations or relative movements between the drive unit and the vehicle body; however, these relative movements must not only be dampened but must also be limited in terms of the distance or deflection to prevent that parts of the drive unit strike against the vehicle body in an undesirable manner. Mounts for a motor vehicle drive unit, which includes a torque roll axis, are also known from DE 40 09 995 A1. Here, the drive unit has two mounts which lie on the torque roll axis, and a further mount which is disposed spaced apart from the torque roll axis. For this purpose, one of the mounts on the torque roll axis serves as a load-carrying bearing to support the weight of the drive unit. The torque roll axis is the axis about which a floating unit exercises a rolling oscillation from the gas forces of the combustion due to the periodic rolling moment excitation. The further mount spaced apart from the torque roll axis causes an additional stabilization via a torque damper.
The object of the present invention is to provide a mounting device for oscillatingly mounting a range extender, which consists of an internal combustion engine and a generator, on a body and a chassis of a motor vehicle by means of vibration-damping elements, which reduces the overall loading of the chassis by eliminating the introduced forces and vibrations via an optimized vibration isolation between the range extender and the vehicle body, while at the same time improving comfort regarding noise and solidity.
This and other objects are achieved according to the invention by a mounting device for oscillatingly mounting a range extender, which consists of an internal combustion engine and a generator, on a body and/or a chassis of a motor vehicle by way of vibration-damping elements, at least two of which are integrated in load-carrying bearings and one additional one is integrated in a supporting bearing for supporting moments. The mounting device is characterized in that the vibration-damping elements of the mounting device at least for the load-carrying bearings are secured to the range extender, i.e. a first vibration-damping element is secured to the internal combustion engine and a second is secured to the generator.
This has the advantage of improving the comfort regarding noise and solidity. In particular with range extenders, which are frequently operated independently of the driving task, it is very important that the acoustics and vibrations of the range extender are designed to make the driving experience for passengers in the vehicle as pleasant as possible.
Advantageous embodiments of the invention provide that the vibration-damping element for the supporting bearing is secured to the range extender. If both load-carrying bearings of the range extender are then still disposed on its torque roll axis, this has the advantage that the mounting optimally isolates the range extender with respect to the acoustics and vibrations, because no constrained motion/vibration is imposed on the unit. The unit oscillates freely about its roll axis, and the load-carrying bearings and the pendulum support transmit significant static forces from accelerations such as gravitational acceleration, transverse acceleration during cornering and/or longitudinal acceleration. If both load-carrying bearings and the supporting bearing of the range extender have a progressive stiffness practically without drag torque in the range from zero to three millimeters on the supporting bearing for damping of torsional vibrations of the range extender about the torque roll axis and both load carrying bearings exert the same restoring moment on the range extender, the invention therefore achieves optimal acoustic and vibrational decoupling. For this purpose, advantageously instead of four unit bearings, according to the prior art for longitudinal support, merely two engine mounts and one pendulum support are required, by which the supporting bearing is connected with the body with the aid of a pivot. This keeps costs low and increases service life, since wear is minimized because only minimal travel is caused in the engine mounts due to the engine rolling oscillation, which contributes to conserving the mounts.
A preferred embodiment of the invention is characterized in that at east one of the two load-carrying bearings is connected with the body via at least one frame. It is therefore easily possible to ensure maximum rigidity of the suspension of the range extender in its longitudinal direction, which is consistent with a lightweight design, while the mounts gently support twisting of the range extender about the torque roll axis in the transverse direction. With such optimal design, the range extender can be operated in a manner such that the passengers in the motor vehicle are unaware of it, which permits pleasant driving conditions and freedom in selecting an efficient operational strategy.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
In all figures, identical technical components are designated with identical reference symbols and all features more closely described can be essential for the invention.